I'm not allowed to cut a tree in my backyard because it's close to power lines, only licensed arborist. I CAN do it but not allowed, so it's just a legislation not an issue of knowledge.
Trimming trees near power lines is extremely dangerous and can lead to deadly electric shocks even simply operating near power lines. Metal ladders and tools can draw current from lines to ground and to a great deal of damage. Arborists have special training and tools to prevent deadly electric shocks when trimming trees near power lines.